s390/bpf,jit: call module_free() from any context

The workqueue workaround is no longer needed. Same as 5199dfe5
"sparc: bpf_jit_comp: can call module_free() from any context".

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>